Extremely low-threshold amplified spontaneous emission of 9,9′-spirobifluorene derivatives and electroluminescence from field-effect transistor structure

By doping 2,7-bis[4-(N-carbazole)phenylvinyl]-9,9'-spirobifluorene (spiro-SBCz) into a wide energy gap 4,4'-bis(9-carbazole)-2,2'-biphenyl (CBP) host, we demonstrate an extremely low ASE threshold of E-th = (0.11 +/- 0.05) mu J cm(-2) (220 W cm(-2)) which is the lowest ASE threshold ever reported. In addition, we confirmed that the spiro-SBCz thin film functions as an active light emitting layer in organic light-emitting diode (OLED) and a field-effect transistor (FET). In particular, we succeeded to obtain linear electroluminescence in the FET structure which will be useful for future organic laser diodes.